Alcohols

Question 1

what are alcohols

Answer 1

saturated organic compounds having C, H, and OH

Question 2

what are monohydric alcohols

Answer 2

they only have 1 OH group
functional group- Cn H2n+1 OH

Question 3

primary alcohol

Answer 3

C atom with OH is bonded to 2H
RCH2OH

Question 4

secondary alcohol

Answer 4

C atom with the OH is bonded to only 1 H atom
R CH(OH) R’

Question 5

tertiary alcohol

Answer 5

C atom with the OH is not bonded to any other H atom
R3COH

Question 6

properties of alcohols

Answer 6

1. all alcohols with up to 11 C atoms are colourless liquid
2. the simpler alcohols (up to 4 C) are soluble in water due to hydrogen bonding
3. as the number of C atoms increases, the non-polar hydrocarbon part becomes bigger so solubility decreases

Question 7

reaction of alcohols with Na metal

Answer 7

the alcohols readily react with Na metal
Na replacethe H of the OH group

Question 8

combustion of alcohols

Answer 8

the alcohols burn readily to produce CO2 + H2O
energy is produced so the alcohols are good fuels

Question 9

reaction with potassium pentachloride or thionylchloride

Answer 9

when an alcohol is warmed with PCl5 or SOCl2, Cl replaces the OH group of the alcohol and HCl fumes are evolved

Question 10

how is the OH group tested for in aliphatic compounds

Answer 10

reaction with PCl5 or SOCl2 is used to confirm the presence of the OH group

Question 11

2 methods of preparing an alcohol

Answer 11

1. the alcohols can be prepared by heating an alkyl halide with NaOH on the reflux
2. the alcohols can be prepared by the addition of steam to an alkene
   the alkene is mixed with steam and then compressed to 70 atm and passed over a catalyst of H3PO4 at 300 deg. C

Question 12

dehydration of alcohols

Answer 12

alcohols are dehydrated to alkenes by heating with an excess amount of conc. H2SO4

during the reaction, H and OH are lost from adjacent C atoms

when secondary and tertiary alcohols are dehydratd with 4 or more C atoms, a mixture of isometric alkenes can be formed

Question 13

oxidation of alcohols

Answer 13

the alcohols can be oxidized by heating with acidified potassium dichromate and H2SO4, or acidified potassium permanganate and H2SO4

Question 14

oxidation of primary alcohol

Answer 14

they have 2H atoms on the C atoms with the OH
oxidation comes from losing the H atoms

the primary alcohols are oxidized to aldehydes and then undergo further oxidation to carboxylic acids

Question 15

oxidation of secondary alcohols

Answer 15

secondary alcohols are oxidized to ketones and can then be further oxidized

Question 16

oxidation of tertiary alcohols

Answer 16

tertiary alcohols cannot be oxidized since the C atoms with the OH group does not have H atoms to lose